First-Come-First-Served (FCFS) Scheduling

Other names of this algorithm are:

First-In-First-Out (FIFO)

Run-to-Completion

Run-Until-Done

Perhaps, First-Come-First-Served algorithm is the simplest scheduling
algorithm is the simplest scheduling algorithm. Processes are dispatched
according to their arrival time on the ready queue. Being a nonpreemptive
discipline, once a process has a CPU, it runs to completion. The FCFS scheduling
is fair in the formal sense or human sense of fairness but it is unfair in the
sense that long jobs make short jobs wait and unimportant jobs make important
jobs wait.

FCFS is more predictable than most of other schemes since it offers time.
FCFS scheme is not useful in scheduling interactive users because it cannot
guarantee good response time. The code for FCFS scheduling is simple to write
and understand. One of the major drawback of this scheme is that the average
time is often quite long.

The First-Come-First-Served algorithm is rarely used as a master scheme in
modern operating systems but it is often embedded within other schemes.